Question

A used car can be purchased by paying $1000 down at the time of purchase, and then paying $200 per month for 25 months. Write an equation that gives the average cost per month as a function of the number of months of ownership.

Answer 1

Let m be the number of months

Since there is a downpayment of $1000, we write the first term of the function for the average cost as

$C(m)=\frac{1000}{m}$

Next we add the $200 cost per month, and we get

$C(m)=\frac{1000}{m}+200$

Lastly, since this is only for 25 months. We establish the domain as 1 ≤ m ≤ 25.

Therefore, the equation is

$C(m)=\frac{1000}{m}+200,1\leq m\leq25$